At the current pace of technological innovation, an electronic device purchased today will likely become obsolete within the next couple of years. This presents a frustrating dilemma to consumers. Rapid obsolescence is perhaps nowhere more apparent than in the personal computer market segment. With new generations of more powerful computers being released every six months to a year, a consumer is wary of paying a premium for a top-of-the-line computer system knowing that in less than a year's time, the same computer will be considered old technology, available to consumers at less than half its retail price at introduction.
One way a consumer can protect their investment in a computer system is to purchase a system having a processor that can be upgraded. For example, a consumer could purchase a 486-based computer system operating at 66 MHz, and later, if more power is desired, upgrade their processor to for example, a 100 MHz 486 processor. For desktop personal computer systems, a consumer may also be able to upgrade their 486 processor-based system to a more powerful, compatible, next generation processor such as a Pentium.RTM. processor, available from Intel Corporation of Santa Clara, Calif. In this manner, some portion of a consumer's initial investment in their desktop computer system is salvaged because the consumer need only purchase a more powerful processor to upgrade their computer system rather than purchasing an entirely new computer system.
Unfortunately, mobile computer systems are not as easily upgradable. Mobile computer systems include, for example, notebook computers, laptop computers, and personal data assistants. In the interest of saving space, the processor, chipset, memory, and various other primary components of the mobile computer system are highly integrated. This high degree of integration makes upgrading any one component of the mobile computer system, such as the processor, technically challenging and expensive, particularly for an upgrade from one processor generation to the next.
For example, FIG. 1 is a prior art computer system in which processor 100 is coupled to and communicates with the primary bridge, bridge A 103, via host bus 108. Bridge 103 couples processor 100 to peripheral component interconnect (PCI) bus agents 1 and 2 by coupling host bus 108 to PCI bus 106, to which the bus agents are coupled. The PCI protocol is described by the PCI Local Bus Specification, Revision 2.0 (1993), and Revision 2.1 (1995). In addition, bridge 103 couples processor 100 and PCI bus agents 1 and 2 to memory 104 by coupling host bus 108 and PCI bus 106 to memory bus 109, to which memory 104 is coupled. In this manner, bridge 103 enables three-way communication between memory 104, processor 100, and PCI agents 1 and 2. Clock 102 is coupled to and provides clock signals to processor 100, primary bridge 103, and PCI agents 1 and 2. A secondary bridge, bridge B 105, is coupled to PCI bus 106 and to secondary bus 107, enabling communication between secondary bus agents 3 and 4, coupled to secondary bus 107, and the rest of the computer system. Secondary bus bridge 105 is also coupled to processor 100 by way of signal line 110. Also, voltage regulator 101 is coupled to and provides a voltage supply to processor 100.
Upgrading processor 100 to a faster processor in the same processor family is simply a matter of removing the old processor and inserting a new processor into the same socket. Upgrading to a next generation processor family, however, is more involved. To effectively upgrade the computer system of FIG. 1 to a next generation processor family, processor 100, primary bridge 103, and possibly clock 102 and voltage regulator 101 may need to be replaced. Secondary bridge 105 may also need to be replaced if its output voltage levels along signal line 110 are not compatible with the upgraded processor's input voltage level specifications. Replacement of all of these components in a mobile system may wind up costing more than the system itself is worth. In addition, the interconnect routings between these components and their corresponding sockets may not support an upgrade.